JP2000138823A - Image processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify video data transfer processing by interleaving data other than bit map data of a line header, to which an identification number and a consecutive line number N are added, so as to compress the data in the case that the same data of a line are in existence consecutively on N lines, thereby decreasing the frequency of access to a memory. SOLUTION: When the same data of a line are in existence consecutively on N lines, an identification number is given to a data block for the consecutive N lines, the identification number and the consecutive line number N are provided as a line header to a head of the data block and other data than bit map data of the line header are interleaved, so as to cause the data to be compressed. A CPU expands the bit map data of each line to an image data storage section 101, compresses the bit map data and stores the compressed data in a compression data storage section 102. When the bit map data that are expanded in the image data signal 101 are compressed, the CPU references a tag and the consecutive line number N of the line header of each line.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus such as a printer or a copier of another function, and more particularly to an improvement in compression efficiency of print bitmap data.

[0002]

2. Description of the Related Art When printing black-and-white document data from a host device to a printer device and printing it, image data of one page is developed in a page buffer of a RAM in a controller of the printer device, and the developed image image data is stored in a page buffer. For all lines from the first line to the last line in the printing direction, binary print image data of white or black is read in order and sent to the printer engine and printed on recording paper.

[0003]

However, if the binary print pixel data of white or black is sequentially read and sent to the printer engine for all the lines irrespective of the content of the developed image data of one page, Video DMA processing for reading all data for one page from the RAM is required. For example, when video DMA transfer is performed for all lines of white data, which are often included in a text file or the like, “0” data indicating white data is replaced with system data. Useless processing has to be performed, such as continuing to send one line via the bus, occupying the system bus and affecting the performance of the entire system. In some cases, the bus for the image memory is dedicated to support the system bus separately from the system bus. However, in this case, the number of data buses increases, and the layout of the substrate and the design of the gate array become complicated and cost increases. .

[0004] It is an object of the present invention to provide an image processing apparatus which can improve such disadvantages, reduce the number of accesses to the memory, simplify the video data transfer processing, and reduce the load on the system bus. is there.

[0005]

An image processing apparatus according to the present invention expands image information from a host apparatus into bitmap data, and transfers the expanded bitmap data line by line in a video DMA to perform image correction. In an image processing apparatus that transmits serial video data to a printer engine and prints an image, when developing image information from a host device into bitmap data, the same data as one line is continuously used for N lines. If it exists, an identification number is assigned to the same data block of N consecutive lines, and the identification number and the number of continuous lines N are given as a line header at the beginning of the same data block, and the identification number and the number of continuous lines N Characters other than the bitmap data of the line header marked with are thinned out and compressed.

It is preferable that the image correction section for performing the image correction has a cache memory for storing video data for M lines, and each line in the cache memory is managed by an identification number assigned to the same data block.

When printing the bitmap data one line at a time, it is preferable to switch the video data in accordance with the identification number of each line header and the number N of continuous lines to expand the compressed data in a pseudo manner.

Further, whether or not the content of the cache memory is cleared every time one page is printed is switched according to the content of the number of copies.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A printer device according to the present invention is connected to a host device and prints print data sent from the host device. The printer device has a controller and a printer engine for performing printing. The controller has a host interface, a CPU, an ASIC, a program ROM, a font ROM, a RAM, an image correction unit, and an engine interface. The RAM has an image data storage unit and a compressed data storage unit. Each of the image data storage unit and the compressed data storage unit has an image data area for storing bitmap data for each line.
It has a 6-bit line header. The upper six bits of the line header indicate an identification number called a tag for monitoring each line, and the lower six bits indicate the number N of continuous lines when the same data as one certain line is continuously present. The image correction unit is R
It is for correcting the video image data on the AM and sending it to the engine interface, and has an input buffer, a video cache memory, an output buffer, a line counter, and a video selector.

When the image information sent from the host device is expanded into bitmap data and stored in the image data storage section of the RAM, the CPU determines that if the same data as a certain line exists continuously for N lines, The same data block of N lines is assigned an identification number, and the identification number and the number N of continuous lines are assigned to the head of the same data block as a line header and developed. When compressing the bitmap data expanded in the image data storage,
The PU thins out and compresses data other than the bitmap data of the line header to which the identification number and the continuous line number N are attached, and stores the data in the compressed data storage unit.

When printing the bitmap data stored in the compressed data storage unit, if the line header tag of each line stored in the image correction unit is the same, the bitmap data is transferred from the compressed data storage unit to the video cache. The memory is loaded only once to reduce the number of DMA transfers. When the line data loaded in the cache memory is printed one line at a time, if a plurality of lines is specified in the continuous line number of each line header, the line data having the same identification number in the cache memory is specified. Output is repeated for the number of lines to increase the efficiency of the printing process.

[0012]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. As shown in the figure, the printer device 1 is connected to a host device 2, prints print data sent from the host device 2, and has a controller 3 and a printer engine 4 for printing. The controller 3 has a host interface 5, a CPU 6, an ASIC 7, a program ROM 8, a font ROM 9, a RAM 10, an image correction unit 11, and an engine interface 12. Host interface 5 is Centro I / F or RS232C
And communicates with the host device 2. The CPU 6 controls the entire controller 3 according to a program in the program ROM 8 and a command from the host device 2. ASI
C7 controls a bus to a device of the controller 3 or an external interface, and controls DMA transfer of bitmap data. Program ROM 8
The control program of the controller 3 and the image correction unit 11
Are stored. Font ROM
Reference numeral 9 stores font pattern data and the like. R
The AM 10 is used as a work memory of the CPU 6, an input buffer for input data, a page memory for print data, and the like. The RAM 10 has an image data storage unit 101 and a compressed data storage unit 102, as shown in FIG. Image data storage unit 101 and compressed data storage unit 1
02 has an image data area 103 for storing bitmap data for each line as shown in FIG. 3, and has a 16-bit line header 104 at the head of each line.
The upper six bits of the line header 104 indicate an identification number called a tag for monitoring each line, and the lower six bits indicate the number N of continuous lines when the same data as one certain line is continuously present.

An image correcting section 11 corrects the image of the video image data on the RAM 10 to perform image correction on the engine interface 1.
2 and includes an input buffer 111, a video cache memory 112, an output buffer 113, a line counter 114, and a video selector 115, as shown in FIG. The input buffer 111 converts bitmap parallel data fetched from the RAM 10 into serial data. The video cache memory 112 stores serial data from the input buffer 111 for a plurality of lines, and each line is managed by a tag of a line header provided at the head of the line. The output buffer 113 outputs the video data output from the video cache memory 112 in synchronization with a video clock. The line counter 114 receives a line gate signal and a video clock, and outputs a trigger signal every time one line of image data is output. The video selector 115 switches and selects video data in the video cache memory 112 according to the information of the line header 104 for each line in response to a trigger signal from the line counter 114. The engine interface 12 communicates commands, statuses and print data with the printer engine 4.

In the printer device 1 configured as described above,
For example, an operation when performing compression processing when printing the table file 21 shown in FIG. 4 will be described. FIG. 4B shows an enlarged view of the head of the print data of the table file 21 shown in FIG. As shown in FIG. 4B, the first line and the first line are the same data of white and black because only the horizontal line on the table file 21 is shown.
Lines 3 to 5 show only vertical lines of the table file 21, and are the same data in which white and black data are repeated.
Since there are fonts in the 50 lines from the line, different data are obtained for each line. Lines 51 to 53 indicate only vertical lines of the table file 21, and are the same data in which white and black data are repeated, and are the same data as lines 3 to 5. Lines 54 and 55 show the same data of white and black because they show only the horizontal lines of the table file 21, and have the same data of lines 1 and 2;
Lines 6 to 58 are the same data in which white and black data are repeated because only the vertical lines of table file 21 are shown.
The data is the same as the 3rd to 5th lines, and since the 59th to 100th lines have fonts, all the lines have different data.

When print data indicating such a table file 21 is sent from the host device 2 to the printer device 1, C
The PU 6 develops the sent print data in the image data storage unit 101 of the RAM 10 as bitmap data line by line. At this time, the CPU 6 decodes each line, and as shown in FIG. 3A, develops the information as a line header 104 by adding 16-bit data to the head of one-line bitmap data. When adding this line header 104, the first line header 1
It is set to “0” indicating that the 04 tag is not used, and the number of continuous lines N is set to “1”. Next, the bit map data of the second line is decoded, and if it is determined that the bit map data of the second line is the same as the bit map data of the first line as shown in FIG. Is set to "1", the number N of continuous lines is set to "2", and the line header 104 is developed as bitmap data without adding the line header 104 to the second line. Next, the bit map data of the third line is decoded, and if it is determined that the bit map data of the third line is different from the bit map data of the first line, the line header 104 of the third line is determined.
Is set to "0", and the number N of continuous lines is set to "1".
Subsequently, the bit map data on the fourth line is decoded, and if it is determined that the bit map data on the fourth line is the same as the bit map data on the third line, the bit map data on the fourth line is compared with the line data of the already set tag. If the tag is equal, the tag is set to “1”, and if not, the tag of the line header 104 of the third line is set to “2”, and the bitmap is added without adding the line header 104 to the fourth line. Expand as data. Similarly, if the bitmap data of the fifth line is decoded and it is determined that the bitmap data of the fifth line is the same as the bitmap data of the third line, the number N of continuous lines is set to “3” and the fifth line is set. Is developed as bitmap data without adding the line header 104 to the data. Thus, the bitmap data of each line is sequentially developed.

When the bitmap data of each line is developed, since the lines 6 to 50 are all different data, the tag is set to “0” in the line header 104 of the line 6 to 50, and N is "1"
To expand the bitmap data. Since lines 51 to 53 are the same data as lines 3 to 5, the tag of the line header 104 of the 51 line is set to “2”, the number N of continuous lines is set to “3”, and the 52 Is developed as bitmap data without adding the line header 104. Since the bitmap data of 54 lines and 55 lines is the same as 1 line and 2 lines, the tag of the line header 104 of 54 lines is set to “1”, the number of continuous lines N is set to “2”, and 56 lines to 58 lines Bitmap data from 3 lines to 5
Since the data is the same as the line, the tag of the 56-line line header 104 is set to “2”, and the number N of continuous lines is set to “3”.

As described above, the image data storage unit 1
01 after expanding the bitmap data of each line,
The PU 6 compresses the decompressed bitmap data and stores it in the compressed data storage unit 102. When compressing the bitmap data expanded in the image data storage unit 101, the CPU 6 refers to the tag of the line header 104 and the number N of continuous lines of each line, and adds the tag of the line header 104 and the number N of continuous lines. For each line, a line header 104 and bitmap data are stored in a compressed data storage unit 102.
Expand to For example, when the bitmap data of each line shown in FIG. 3 is compressed, as shown in FIG. 4, the tag is “1” on the first line and the line header 104 with the number N of continuous lines is “2” and the first line The bitmap data is stored in the compressed data storage unit 102, the bitmap data of the second line is not stored in the compressed data storage unit 102, and the tag is “2” in the second line of the compressed data storage unit 102 and the number of continuous lines. The line header 104 where N is set to “3” and the bitmap data of the third line are developed, and the bitmap data of the fourth and fifth lines are cut. In addition, since the tag of the line header 104 of 6 to 50 lines is “0” and the number N of continuous lines is “1”, it is stored in the compressed data storage unit 102 as it is. In this way, the line in which the same data is continuous is cut and the line header 104 is cut.
Is stored in the compressed data storage unit 102, thereby cutting 11 lines of data from the 1st to 100th lines of the print data of the table file 21 shown in FIG. When one line has 2024 bits (253 bytes), 2,783 bytes of data can be compressed.

The operation for printing the compressed bitmap data in the compressed data storage unit 102 of the RAM 10 as described above will be described with reference to the flowchart of FIG.
When the printing operation is started, the CPU 6 sets the compressed data storage 1
The line header 104 of the first line stored in the first line 02 is transferred to the video selector 115 of the image correction unit 11 (steps S1 and S2). Video selector 115
Determines whether the tag of the transferred line header 104 is "0" (step S3). If the tag of the line header 104 is not "0", the line data is added to the address of the corresponding tag in the video cache memory 112. Is checked (step S4). As a result of this check, if there is no line data at the address of the corresponding tag in the video cache memory 112, the video DMA request is sent to the ASI
Issue to C7. That is, since the tag of the line header 104 of the first line stored in the compressed data storage unit 102 is “1” and there is no line data at the address of the tag “1” of the video cache memory 112,
An MA request is issued to the ASIC 7, and the line header 104 and bitmap data of the first line from the compressed data storage unit 102 are transferred to the video cache memory 112 via the input buffer 111, and the tag of the video cache memory 112 is set to "1". (Step S5). The data for one line loaded into the output port of the video cache memory 112 is sent as video data to the engine interface 12 via the output buffer 113, and the first line is printed by the printer engine 4 (step S7). Further, since the number of continuous lines N of the first line header 104 loaded in the video cache memory 112 is “2”, the number of lines is set to +1 and one line continuously loaded to the output port of the video cache memory 112 is set. The minute data is sent to the engine interface 12 as video data via the output buffer 113 and the printer engine 4 prints the second line (step S).
8, S9, S7). Next, the line header 104 of the third line stored in the second line of the compressed data storage unit 102
Is transferred to the video selector 115 (steps S10 and S10).
11, S2) 3 in the same manner as the first and second lines
The fourth line and the fifth line are printed (steps S3 to S5, S7 to S9).

When printing the sixth to fiftieth lines, the video selector 115 determines that the tag of the transferred line header 104 is "0" (step S).
2, S3), the bitmap data stored in the compressed data storage unit 102 is loaded into the output port of the video cache memory 112 by video DMA transfer for each line via the input buffer 111 (step S1).
2) The data for one line loaded into the output port of the video cache memory 112 is stored in the output buffer 1
The data is sent as video data to the engine interface 12 via the printer interface 13 and printed by the printer engine 4 (steps S13 and S14).

When printing the 51st line, when the video selector 115 detects that the tag of the transferred line header 104 is “2” (steps S2 and S3), the video selector 115 determines that the tag of the video cache memory 112 is “2”. Load the line data at the address to the output port (step S
6) The data of one line loaded into the output port of the video cache memory 112 is stored in the output buffer 1
The data is sent to the engine interface 12 as video data via the printer 13 and printed by the printer engine 4 (step S7). Since the number N of continuous lines of the 51st line is “3”, the same data is transmitted to the engine interface 12 as video data through the output buffer 113 twice in succession, and the 51st line, the 52nd line, and the 53rd line. The same data for the third line is printed (steps S8, S9, S7). When printing the 54th line, the video selector 115 detects that the tag of the transferred line header 104 is “1” (Step S).
2, S3), the line data at the address of which the tag of the video cache memory 112 is "1" is loaded into the output port (step S6), and the video cache memory 11 is loaded.
2 is sent to the engine interface 12 as video data via the output buffer 113 via the output buffer 113, and the printer engine 4
(Step S7). In this case, since the number of continuous lines N of the 54th line is “2”, the same data is continuously output from the video cache memory 112 and
Print the fifth line (steps S8, S9, S
7).

Thus, the compressed data storage unit 102
If the tag of the line header 104 of each line is the same, the bitmap data can be loaded from the compressed data storage unit 102 to the video cache memory 112 once. The burden can be reduced.

In the same manner, the data of each line is printed, all the lines of the table file 21 are printed (step S11), and if only one copy of the table file 21 is to be printed,
Since the file to be printed next time is not the same data, there is no compatibility between the tag of the line header 104 of the bitmap data compressed for the next printing and the tag stored in the video cache memory 112 and the line data. All contents of the video cache memory 112 are cleared (steps S15 and S16). Table file 2
When printing a plurality of copies of “1”, since the file to be printed next is the same data, the tag of the line header 104 of the bitmap data compressed for printing and the tag and line stored in the video cache memory 112 are used. Due to data compatibility, all contents of the video cache memory 112 are stored without being cleared. By storing all the contents of the video cache memory 112 in this manner, it is not necessary to load the bitmap data of each line from the compressed data storage unit 102 to the video cache memory 112, and printing can be performed efficiently. .

[0023]

According to the present invention, as described above, a certain
When the same data as the line exists continuously for N lines,
An identification number is assigned to the same data block of continuous N lines, and the identification number and the number of continuous lines N are provided as a line header at the beginning of the same data block, and the line header with the identification number and the number of continuous lines N attached The bitmap data other than the bitmap data is thinned and compressed, so that the bitmap data can be efficiently compressed.

Also, by managing each line in the cache memory for storing a plurality of lines of video data in the image correction unit for performing image correction by using an identification number assigned to the same data block of the bitmap data, the same bitmap can be obtained. It is good to load the data once into the cache memory.
The burden on the system bus can be reduced by reducing the number of MA transfers.

Further, when printing the print bitmap data one line at a time, if a plurality of lines is specified as the number of continuous lines in each line header, the line data of the same identification number in the cache memory is specified. By repeatedly outputting the data for the number of lines, the efficiency of the printing process can be increased.

Also, by switching whether or not the contents of the cache memory are cleared every time one page is printed according to the content of the number of copies, and when printing a plurality of copies, the entire contents of the video cache memory are saved. It is not necessary to load the bitmap data of each line into the video cache memory, and printing can be performed efficiently.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of a RAM and an image correction unit.

FIG. 3 is an explanatory diagram of bitmap data developed in a RAM.

FIG. 4 is an explanatory diagram of a table file to be printed.

FIG. 5 is a flowchart illustrating a printing process.

[Explanation of symbols]

 Reference Signs List 1 printer device 2 host device 3 controller 4 printer engine 5 host interface 6 CPU 7 ASIC 8 program ROM 9 font ROM 10 RAM 11 image correction unit 12 engine interface 101 image data storage unit 102 compressed data storage unit 111 input buffer 112 video cache memory 113 Output buffer 114 Line counter 115 Video selector

Continued on the front page F-term (reference) 2C087 AA09 AB05 BA02 BA03 BC01 BD40 BD41 BD46 CA05 5B021 AA01 AA30 BB02 BB11 BB12 BB14 CC08 DD02 DD14 5B047 AA01 AB01 EA02 EB05 EB17 5C076 AA21 BA02 BA03 DA02 BA03 BB04 DA06

Claims (4)

[Claims] An image information from a host device is developed into bitmap data, and the developed bitmap data is converted into one bitmap data.
In an image processing apparatus that transmits serial video data that has undergone image correction by line-by-line video DMA transfer and image correction to a printer engine to print an image, when image information from a host device is expanded into bitmap data, If the same data as the line exists continuously for N lines, an identification number is assigned to the same data block of the continuous N lines, and the identification number and the number of continuous lines N
An image processing apparatus, wherein a line header is provided at the beginning of the same data block, and data other than the bitmap data of the line header to which the identification number and the continuous line number N are attached is thinned out and compressed. 2. An image correcting section for performing the image correction, comprising a cache memory for storing video data for M lines, wherein each line in the cache memory is managed by an identification number assigned to the same data block. 2. The image processing device according to 1. 3. The image processing according to claim 1, wherein when the bitmap data is printed one line at a time, video data is switched according to the identification number of each line header and the number N of continuous lines to expand the compressed data in a pseudo manner. apparatus. 4. The image processing apparatus according to claim 3, wherein whether or not the contents of the cache memory are cleared each time one page is printed is switched according to the contents of the number of copies.